First Online: 18 July 2013Received: 18 February 2013Accepted: 17 July 2013

Abstract

BackgroundStandard MRI has been used for high-grade gliomas detection, albeit with limited success as it does not provide sufficient specificity and sensitivity to detect complex tumor structure. Therefore targeted contrast agents based on iron oxide, that shorten mostly T2 relaxation time, have been recently applied. However pulse sequences for molecular imaging in animal models of gliomas have not been yet fully studied. The aim of this study was therefore to compare contrast-to-noise ratio CNR and explain its origin using spin-echo SE, gradient echo GE, GE with flow compensation GEFC as well as susceptibility weighted imaging SWI in T2 and T2* contrast-enhanced molecular MRI of glioma.

MethodsA mouse model was used. U87MGdEGFRvIII cells U87MG, derived from a human tumor, were injected intracerebrally. A 9.4 T MRI system was used and MR imaging was performed on the 10 day after the inoculation of the tumor. The CNR was measured prior, 20 min, 2 hrs and 24 hrs post intravenous tail administration of glioma targeted paramagnetic nanoparticles NPs using SE, SWI, GE and GEFC pulse sequences.

ResultsThe results showed significant differences in CNR among all pulse sequences prior injection. GEFC provided higher CNR post contrast agent injection when compared to GE and SE. Post injection CNR was the highest with SWI and significantly different from any other pulse sequence.

ConclusionsMolecular MR imaging using targeted contrast agents can enhance the detection of glioma cells at 9.4 T if the optimal pulse sequence is used. Hence, the use of flow compensated pulse sequences, beside SWI, should to be considered in the molecular imaging studies.